1. Field of the Invention
Aspects of the present invention relate to a gel electrolyte, and a dye-sensitized solar cell using the same.
2. Description of the Related Art
Generally, dye-sensitized solar cells include: a photocathode having a semiconductor oxide nano particle layer, to which dye molecules are adsorbed; a counter electrode including a Pt catalyst; and an electrolyte including redox ion couples. The electrolyte greatly contributes to the photoelectric conversion efficiency and durability of solar cells. In this regard, liquid electrolytes are commonly used in solar cells.
However, a volatile organic solvent, included in liquid electrolytes, easily volatilizes or leaks, thereby deteriorating the durability of solar cells including such liquid electrolytes. Thus, there is a need for a non-volatile, ionic gel electrolyte, in order to improve the durability of dye-sensitized solar cells.
Methods of preparing ionic gel electrolytes include: a method of gelling a liquid electrolyte by adding nano particles to the liquid electrolyte; a method of gelling a liquid electrolyte by adding a polymer to the liquid electrolyte; a method of solidifying a liquid solvent by adding a gelling agent to the liquid solvent; and a method of polymerizing or crosslinking monomers, via chemical bonds (US 20030145885A). Among these methods, an ionic gel electrolyte, prepared by adding a polymer to the liquid electrolyte, has far less ion conductivity than the liquid electrolyte.
According to the method of solidifying the liquid solvent by adding a gelling agent, the stability of the solvent may be decreased, as the temperature is increased. According to the method of polymerizing or crosslinking monomers via chemical bonds, the temperature should be increased, and an initiator should be added thereto, in order to initiate reactions after injecting the monomers into cells. Thus, the efficiency of solar cells may be decreased, and unreacted materials may reduce the durability of the solar cells. According to the method of gelling a liquid electrolyte by adding nano particles to the liquid electrolyte, the gelation properties of the electrolyte are not satisfactory, even though the ion conductivity is excellent.